Print method and system to obtain high quality image using less data quantity

ABSTRACT

A printer is permitted to obtain printed matter of high picture quality from print data transferred in the state changed into 1 bit for the purpose of shortening data transfer time. A multi-value conversion unit ( 23 ) converts CMYK respective 1 bit binary data from an expansion unit ( 22 ) into multi-valued data. The multi-value conversion unit sets values that a remarked pixel should take, which corresponds to circumstances of surrounding pixels, in a table where two gradation data (0, 1) of the remarked pixel and two gradation data of pixels around the remarked pixel, e.g., upper and lower, left and right and oblique eight pixels are assigned to respective digits of binary number of eight figures are taken as parameter to make reference to this table to thereby convert two gradation data into multi-valued data.

TECHNICAL FIELD

The present invention relates to a printer and a print method which havemulti-valued representation ability per one pixel, and relates to aprinter, a print method and a print system which can obtain printedmatter of high picture quality by less data quantity.

This application claims priority of Japanese Patent Application No.2001-356527, filed on November, 2001, the entirety of which isincorporated herein.

BACKGROUND ART

Picture quality of printed result (printed matter) required for printerbecomes high year by year, and realization of high resolution andrealization of multi-valued data are advanced in accordance therewith.

On the other hand, correspondingly thereto, print data becomes vast moreand more. For example, data quantity of A4 full size 600 dpi CMYK (cyan,magenta, yellow, black) respective pixel 8 bit becomes equal to as faras about 140 MB. Under such circumstances, it takes much time in datatransfer. In view of the above, compression is implemented to such data,or 8 bits are changed into 4 bits or 3 bits to thereby reduce dataquantity.

However, even if data quantity is halved by compression and is furtherchanged into 3 bits so that it becomes equal to ⅜, there still existsdata quantity of about 26 MB. As a result, it took much time in datatransfer.

In view of the above, when respective pixels are caused to be changedinto 1 bit so that data quantity is further halved by compression, dataquantity is held down to about 9 MB. Accordingly, it is possible toshorten data transfer time down to satisfactory degree. However, sincerespective pixels are represented by binary number, it becomes difficultto obtain printed matter of high picture quality.

DISCLOSURE OF THE INVENTION

The present invention is proposed in view of the actual circumstances asdescribed above, and its object is to provide a printer which can obtainprinted matter of high picture quality from print data which has beentransferred in the state changed into 1 bit for the purpose ofshortening data transfer time.

Another object of the present invention is to provide a print method ofobtaining printed matter of high picture quality from print datatransmitted in the state where data quantity is caused to be 1 bit forthe purpose of shortening data transfer time.

A further object of the present invention is to provide a print systemwhich performs data transfer in the state where data quantities ofrespective pixels are caused to be 1 bit, and which can obtain printedmatter of high picture quality from data of 1 bit of respective pixelswhich have been caused to undergo data transfer.

The printer according to the present invention proposed in order toattain the above-described objects is directed to a printer which canmake representation having three gradations or more by one pixel, whichcomprises multi-value conversion means for converting data of twogradations of a remarked pixel into data of multi-gradation includingthree gradations or more on the basis of data of pixels around theremarked pixel, and recording head means for performing print operationbased on the data of multi-gradation from the multi-value conversionmeans.

In the printer, values that the remarked pixel should take, which arebased on data of surrounding pixels, are set in advance in a table wherevalues in which two gradation data (0, 1) of plural n (n is integer ofthree or more) pixels around the remarked pixel are assigned torespective digits of binary number of n figures and two gradation data(0, 1) of the remarked pixel are taken as parameter. Thus, themulti-value conversion means makes reference to this table to therebyconvert two gradation data into multi-gradation data. For example, n is8, and eight pixels positioned in upper and lower directions, in leftand right directions and in oblique direction of the remarked pixel arecaused to be pixels to be converted.

The print method according to the present invention proposed in order toattain the above-described objects is directed to a print method appliedto a printer which can make representation having three gradations ormore by one pixel, which comprises a multi-value conversion step ofconverting data of two gradations of the remarked pixel into data ofmulti-gradation including three gradations or more on the basis of dataof pixels around the remarked pixel, and a recording step of performingprint operation based on data of multi-gradation from the multi-valueconversion step.

In the print method, values that the remarked pixel should take, whichare based on data of surrounding pixels, are set in advance in a tablewhere values in which two gradation data (0,1) of plural n (n is integerof 3 or more) around the remarked pixel are assigned to respectivedigits of binary number of n figures and two gradation data (0, 1) ofthe remarked pixel are taken as parameter to make reference to the tableat the multi-value conversion step to thereby convert two gradation datainto multi-gradation data. For example, n is 8, and 8 pixels positionedin the upper and lower directions, in the left and right directions andin oblique direction of the remarked pixel are assumed to be pixels tobe converted.

Another printer according to the present invention is directed to aprinter adapted for receiving data based on image transferred throughtransfer means to perform print operation in conformity with that data,which comprises multi-value conversion means for converting data of twogradations of a remarked pixel transferred through the transfer meansinto data of multi-gradation including three gradations or more on thebasis of data of pixels around the remarked pixel, and recording headmeans for performing print operation based on the data of themulti-gradation from the multi-value conversion means.

Another print method according to the present invention is directed to aprint method applied to a printer adapted for receiving data based onimage transferred through transfer means to perform print operation inconformity with data, which comprises a multi-value conversion step ofconverting data of two gradations of a remarked pixel transferredthrough the transfer means into data of multi-gradation including threegradations or more on the basis of data of pixels around the remarkedpixel, and a recording step of performing print operation based on dataof multi-gradation from the multi-value conversion step.

The print system according to the present invention is directed to aprint system adapted for transferring data based on image to a printerthrough transfer means to perform print operation in conformity with thedata at the printer, wherein image is caused to be data of twogradations per one pixel, and is then transferred to the printer throughthe transfer means, whereby the printer converts data of two gradationsof a remarked pixel into data of multi-gradation including threegradations or more on the basis of data of pixels around the remarkedpixel.

In this print system, values that the remarked pixel should take, whichare based on data of surrounding pixels, are set in advance in a tablewhere values in which two gradation data (0, 1) of plural n (n isinteger of 3 or more) pixels around the remarked pixel are assigned torespective digits of binary number of n figures and two gradation data(0, 1) of the remarked pixel are taken as parameter, whereby multi-valueconversion means makes reference to the table to thereby convert twogradation data into multi-gradation data.

In the print system of the present invention, in transmitting recordingimage data from, e.g., computer device to a printer which can recordmulti-valued (trinary or more) data, the recording image data isconverted into CMYK data on the computer device thereafter to convert itinto binary (1 bit) data of respective colors by using error diffusionmethod, etc. to compress this data or add other information thereto asoccasion demand to send the data thus obtained to the printer.

Further, in the multi-value recordable printer, conversion ofbinary→multi-value is performed by dot arrangement around pixels desiredto be recorded to thereby permit multi-value recording.

By using the print method of the present invention, even if originalimage is data of RGB respective colors 8 bits, such data results in dataof CMYK respective colors 1 bit. Accordingly, data quantity can bereduced to much degree. In addition, in performing print operation byprinter, there results multi-valued image in place of binary image.Accordingly, print quality can be extremely improved as compared tosimple binary image.

In the printer, in conversion of binary→multi-value, values thatremarked pixel should take, which corresponds to circumstances ofsurrounding pixels, are set in table where binary data (0, 1) of theremarked pixel and values in which binary data (0, 1) of eight pixelsaround (positioned in the upper and lower directions, in left and rightdirections and in oblique direction) of the remarked pixel are assignedto respective digits of binary number of eight figures are taken asparameter to make reference to this table to thereby convert binary datainto multi-valued data, thus making it possible to simplify processing,and making it possible to make setting of high degree of freedomcorresponding to surrounding pixels.

As a result, not only conversion of binary→multi-value is performed, butalso edge processing such that density is lowered at the contour portionof the solid portion, etc. can be simultaneously performed.

Still further objects of the present invention and practical meritsobtained by the present invention will become more apparent from thedescription of the embodiments which will be given below with referenceto the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a print system to which the presentinvention has been applied.

FIG. 2 is a block diagram of a computer device constituting the printsystem.

FIG. 3 is a functional block diagram of printer constituting the printsystem.

FIGS. 4A and 4B are views for explaining preparation of multi-valueddata in conformity with multi-value conversion method which constitutesbasis of multi-value conversion processing that multi-value conversionunit of the printer performs.

FIGS. 5 to 28 are views showing a portion of first practical example oftable in which data prepared as the result of preparation ofmulti-valued data are stored.

FIGS. 29 to 37 are views for explaining practical example of multi-valueconversion processing that the multi-value processing unit of theprinter performs with reference to the first practical example of thetable.

FIG. 38 is a view showing a second practical example of table in whichdata prepared as the result of preparation of multi-valued data arestored.

FIGS. 39 to 44 are views for explaining practical example of multi-valueconversion processing that the multi-value conversion unit of theprinter performs with reference to the second practical example of thetable.

FIG. 45 is a view in which processing performed in the print system arecollected.

FIG. 46 is a view in which processing performed in the conventionalprint system are collected.

FIG. 47 is a cross sectional perspective view of practical example ofink jet printer using line head.

FIG. 48 is a cross sectional side view of practical example of ink jetprinter.

FIG. 49 is a block diagram of electric circuit unit of the ink jetprinter.

FIG. 50 is an exploded perspective view of head chip module provided atthe line head.

FIG. 51 is a schematic plan view showing, in an enlarged manner, theessential part of head chip module provided at the line head.

FIG. 52 is an exploded perspective view showing, in an enlarged manner,the essential part of head chip module provided at the line head.

FIG. 53 is a schematic cross sectional view showing, in an enlargedmanner, the essential part of head chip module provided at the linehead.

FIG. 54 is a schematic cross sectional view showing line head.

FIG. 55 is a perspective view of another practical example of the linehead.

FIG. 56 is a cross sectional view showing one structure example of theline head.

FIG. 57 is a cross sectional view showing a further structure example ofthe line head.

FIG. 58 is an outer appearance perspective view of other practicalexample of ink jet printer.

FIGS. 59A to 59C are views showing printed result obtained by the printsystem.

FIGS. 60A and 60B are views showing printed result relating to blurringobtained by the print system.

BEST MODE FOR CARRYING OUT THE INVENTION

Explanation will now be given with reference to the attached drawings inconnection with embodiments of the present invention.

In the embodiments, the present invention is applied to a print systemusing printer which can represent three gradations or more by one pixelas practical example of a printer and a print method to which thepresent invention has been applied.

As shown in FIG. 1, this print system 1 comprises a storage unit 2 inwhich image file 2 a consisting of RGB image data, etc. are stored, acomputer device 10 for implementing color conversion or γ-correction tothe RGB image data of the image file 2 a of the storage unit 2, and forimplementing binarization data processing, etc. to the color-convertedimage data, and a printer 20 for converting binary (1 bit) data ofrespective colors into multi-valued data to have ability to representthree gradations or more per one pixel.

The storage unit 2 is composed of, e.g., hard disc unit or optical discunit, and serves to read out image file 2 a consisting of data of Rcomponent, G component and B component (RGB image data) which arerecorded on the hard disc or the optical disc, etc. to deliver it to thecomputer device 10 as original image. It is a matter of course thatthere may be employed an approach to read out image file from memorymeans, e.g., memory such as RAM, etc., hard disc or optical disc, etc.included within the computer device 10 in place of the storage unit 2 toreproduce it. Namely, it should be noted that the form of the storageunit 2 in which the image file is preserved is not limited by FIG. 1.

The computer device 10 is composed of, e.g., personal computer (PC).When user gives an instruction to print original image on the computerdevice 10, the computer device 10 converts the original image from dataof RGB respective 256 values into data of CMYK (cyan, magenta, yellow,black) respective 256 values by using three-dimensional look-up table,etc. In this instance, γ-correction is also implemented in conformitywith the characteristic of the printer. Data of CMYK 256 respectivevalues are converted into CMYK respective binary data by using wellknown half-toning technology (error diffusion method, or pattern Dithermethod, etc.).

The computer device 10 compresses the binarized data in order to furtherimprove transfer efficiency to add information required for performingprint operation (information such as the number of papers to be printed,resolution at the time of printing, start position, end of data, and/ornew page signal, etc.) to generate print data.

The printer 20 receives the print data which has been caused to undergodata transfer from the computer device 10 to take out informationnecessary for performing print operation from the print data, and toexpand the compressed image data to change it back into CMYK respectivebinary data.

The printer 20 further converts this binary (binarized) data into, e.g.,quinary data on the basis of multi-value conversion method which will bedescribed later. These data are sorted in drive order of the printerhead to send it to the printer head to perform print operation.

As interface between the computer device 10 and the printer 20, theremay be used, e.g., IEEE Std. 1284 (popularly speaking “Centronics”,Bi-Centronics, Small Computer System Interface (popularly speaking“SCSI”), RS-232C or RS-422A, IEEE 1394, Ethernet (registered trademark), Bluetooth, IEEE 802.11a, IEEE 802.11b, and/or USB (UniversalSerial Bus), etc.

The functional block diagram of the computer device 10 is shown in FIG.2. The computer device 10 comprises a color conversion+γ-correction unit11 for implementing color conversion processing and γ-correction to RGBimage data of image file 2 a, a half-toning processing unit 12 forimplementing half-toning processing to CMYK respective 8 bits deliveredfrom the color conversion+γ-correction unit 11, and a header, etc.addition & compression unit 13 for adding header, etc. to the CMYKrespective binary data from the half-toning processing unit 12 tocompress the binary data thus obtained.

The color conversion+γ-correction unit 11 converts RGB image data ofrespective 8 bit 256 values of image file 2 a into data of cyan (C)component, data of magenta (M) component and data of yellow (Y)component respectively consisting of 8 bits which are complementarycolors of three primary colors (red, green, blue) by using, e.g.,three-dimensional look-up table, etc. to further generate data of black(K) component of 8 bits from data of these components. In addition, thecolor conversion+γ-correction unit 11 implements signal processing suchas color correction and/or γ-correction, etc. to data of cyan (C)component, data of magenta (M), data of yellow (Y) component.

The half-toning processing unit 12 converts the data of cyan (C)component, the data of magenta (M) component, the data of yellow (Y)component and the data of black (K) component into binary data ofrespective 1 bits by using the half-toning technology, e.g., errordiffusion method or pattern Dither method, etc.

The header, etc. addition & compression unit 13 compresses CMYKrespective binary data from the half-toning processing unit 12 in orderto further improve transfer efficiency to add information necessary forperforming the print thereto as header to generate print data D_(PR).

Then, the functional block diagram of the printer 20 is shown in FIG. 3.The printer 20 comprises an expansion unit 22 for expanding compressedimage data included in the print data D_(PR), a multi-value conversionunit 23 for allowing CMYK respective 1 bit binary data which are outputsfrom the expansion unit 22 to be multi-valued data, a sorting unit 24for sorting CMYK respective multi-valued data from the multi-valueconversion unit 23, and printer head 21 driven by head drive data D_(HD)which is output from the sorting unit 24.

The expansion unit 22 receives print data O_(PR) which has been causedto undergo data transfer from the computer device 10 to take outinformation necessary for performing print operation from the print dataD_(PR), and to expand the compressed image data to change it back intoCMYK respective 1 bit binary data.

The multi-value conversion unit 23 converts CMYK respective 1 bit binarydata from the expansion unit 22 into, e.g., quinary or sexenary data onthe basis of multi-value conversion method which will be describedlater. In the multi-value conversion method, values that remarked pixelshould take, which corresponds to circumstances of surrounding pixels,are set in table where two gradation data (0, 1) of the remarked pixeland values in which two gradation data of pixels around the remarkedpixel, e.g., eight pixels positioned in the upper and lower directions,in the left and right directions and in oblique direction are assignedto respective digits of binary number of 8 figures are taken asparameter to make reference to this table to thereby convert twogradation data into quinary data. This multi-value conversion methodwill be described later in detail.

The sorting unit 24 sorts CMYK respective multi-valued data from themulti-value conversion unit 23 in drive order of the print head 21 togenerate head drive data D_(HD) to send it to the print head 21.

The print head 21 receives the head drive data D_(HD) to print, onto apredetermined recording paper, image that user has designated at thecomputer device 10.

Then, the detail of the multi-value conversion method which constitutesbasis of multi-value conversion processing that the multi-valueconversion unit 23 performs will be explained. In image binarized by theerror diffusion method, etc., since isolated dots are printed at theportion where density is low, and density of dot is increased accordingas density becomes high, it is possible to allow remarked pixel to havemulti-value in accordance with dot density and bit arrangement aroundthe remarked pixel.

Let assume that value of binary remarked pixel is A and values of eightpixels therearound (positioned in upper and lower directions, in leftand right directions and in oblique direction) are B1, B2, B3, B4, B5,B6, B7, B8 as shown in FIG. 4A. Here, B is binary number and Bs arearranged as shown in FIG. 4B. Further, T[A][B] is caused to be remarkedpixel after multi-value processing, and values suitable for combinationof respective AB with respect to value B of 8 pixels around the binary(binarized) remark pixel A is set at table to thereby determinemulti-valued remarked pixel A′ as follows.A′=T [A][B]As stated above, since the multi-value conversion unit 23 performsmulti-value conversion processing using table in this way, it ispossible to convert binary remarked pixel into multi-value withoutcomplicated conditional branch.

Here, binary (two gradations) data of the remarked pixel and thesurrounding pixels are compared with each other to represent highdensity/low density. Hereinafter, for brevity of explanation, highdensity is changed into black as expression and low density is changedinto white as expression as occasion demands. It is to be noted that, inthe case of C, M, Y, there result C of high density, M of high densityand Y of high density.

In FIGS. 5 to 28, there are shown first practical examples of tableswhere binarized A, value B of eight pixels therearound, binary number ofB (corresponding to FIG. 4B), and value of multi-valued remarked pixel T[A][B] which has been set are stored. It is to be noted that this tableis merely one example, and it is therefore desirable to individuallyprepare optimum tables by binarization processing method and/orspecification of the printer (size of dot, density of dot, resolution,etc.). In this example, value of the multi-valued remarked pixel T[A][B] is set to quinary data from 0 to 4. This is because the value ofthe multi-valued remarked pixel is caused to be in correspondence withgradation representation ability, i.e., quinary data here of the printer20.

FIGS. 5 to 16 show values of multi-valued remarked pixel T [A][B] whenvalues of surrounding eight pixels B are 0 to 255 (00000000 to 11111111)with respect to the fact that value of binarized remarked pixel A is 0.When the value of the binarized remarked pixel A is 0, value ofmulti-valued remarked pixel T [A][B] is caused to be equal to zero inmost cases. However, in this example, at “90, 91, 94, 95, 122, 123, 126,127, 218, 219, 222, 223, 250, 251, 254, 255” where at least upper andlower, and left and right four values (B2, B4, B5, B7) of the value B ofthe surrounding eight pixels are 1, value of the A is set to 1.

FIGS. 17 to 28 show value of multi-valued remarked pixel T [A][B] whenvalues of the surrounding eight pixels B are 0 to 255 (00000000 to11111111) with respect to the fact that value of binarized remarkedpixel A is 1. In this case, there exits feature as recited below. First,when A=1 and B=0, i.e., when value of remarked pixel A is black (1) sizeof two gradations and all of surrounding pixels are white (00000000)side, the value of remarked pixel T [A][B] is caused to be value (1) inthe vicinity of the minimum value of multi-gradation. In addition, thatvalue may be set to minimum value (0).

When A=1 and B=255, i.e., when value of the remarked pixel is black (1)side of two gradations and all of surrounding pixels are black(11111111) side, value of the remarked pixel T [A][B] is set to themaximum value (4) of multi-gradation. In addition, that value may be setto value (3) in the vicinity of the maximum value.

At 90, 91, 94, 95, 122, 123, 126, 127, 218, 219, 222, 223, 250, 251,254, 255” where A=1 and at least upper and lower, and left and rightfour values (B2, B4, B5, B7) of value B of surrounding eight pixels are1, value of the remarked pixel T [A][B] is set to value (3) in thevicinity of the maximum value of multi-gradation. In addition, thatvalue may be set to the maximum value (4).

A practical example of multi-value conversion processing that themulti-value conversion unit 23 performs when value of the binaryremarked pixel A is equal to zero and that value is equal to 1 is shownbelow.

First, the practical example when A is equal to zero will be explainedby using FIGS. 29, 30, 31 and 32.

This processing is a processing such that, e.g., binary data of C (cyan)is delivered from the expansion unit 22 to the multi-value conversionunit 23 in FIG. 3 to make reference to the table at the multi-valueconversion unit 23 to convert binary data of C (cyan) into quinary data.

When A is 0 and B is 10 (binary number: 00001010) as shown in FIG. 29,the multi-value conversion unit 23 takes out T [1][10] from the tableshown in FIG. 5 to allow remarked pixel A′ to be equal to 0.

When A is 0 and B is 63 (binary number: 0011111) as shown in FIG. 30,the multi-value conversion unit 23 takes out T [0][63] from the tableshown in FIG. 7 to allow remarked pixel A′ to be equal to 0.

When A is 0 and B is 95 (binary number: 01011111) as shown in FIG. 31,the multi-value conversion unit 23 takes out T [0][95] from the tableshown in FIG. 9 to allow remarked pixel A′ to be equal to 1.

When A is 0 and B is 255 (binary number: 11111111) as shown in FIG. 32,the multi-value conversion unit 23 takes out T [0][255] from the tableshown in FIG. 15 to allow remarked pixel A′ to be equal to 1. This isbecause the case where thin pixel (1) exists at the solid portion ismore natural than the case where 0 exists thereat in dependency uponimage.

Then, practical example when A=1 will be explained by using FIGS. 33, 34and 35.

This processing is also a processing such that, e.g., binary data of C(cyan) is delivered from the expansion unit 22 to the multi-valueconversion unit 23 in FIG. 3 to make reference to the table at themulti-value conversion unit 23 to convert binary data of C (cyan) intoquinary data.

When A is 1 and B is 0 (binary number: 00000000) as shown in FIG. 33,the multi-value conversion unit 23 takes out T [A][B] from the tableshown in FIG. 17 to allow remarked pixel A′ to be equal to 1.

When A is 1 and B is 255 (binary number: 11111111) as shown in FIG. 34,the multi-value conversion unit 23 takes out T[A][B] from the tableshown in FIG. 28 to allow remarked pixel A′ to be equal to 4.

When A is 1 and B is 90 (binary number: 01011010) as shown in FIG. 35,the multi-value conversion unit 23 takes out T[A][B] from the tableshown in FIG. 21 to allow remarked pixel A′ to be equal to 3.

Methods of determining value of T[A][B] in setting of table arevariously conceivable. In this case, if there is employed such anapproach that when there are many values of 1 as values of surroundingpixels (positioned in upper and lower directions, in left and rightdirections and in oblique direction), large number is set, and whenthere are less values of 1 as such value, small value is set, theportion where density is low is permitted to be thinner and the portionwhere the density is high is permitted to be thicker. Thus, it ispossible to increase gradation as compared to the case of binary data.

Moreover, when the distance between dots is apart from each other, evenin the case of a pattern such that values of surrounding eight pixelsare similar to each other, there are instances where it is preferable totake number smaller than that of the distance between dots is narrow.This is the case as shown in FIG. 36. When A is 1 and B is 165(10100101), the portion positioned obliquely with respect to A amongvalues of surrounding eight pixels is 1. This is similar to the case ofT[1][90] shown in FIG. 35 as pattern. In the case of T[1][90], values of1 exist at upper and lower positions and at left and right positions,and that value is therefore set to 3. However, at the time of T[1][165]shown in FIG. 36, since values of 1 exist at oblique positions.Accordingly, the distance between dots is apart from each other. Thus,when there is employed a method in which that value is rather set to thesame value as T[1][0] shown in FIG. 33, or value in the vicinitythereof, gradation change becomes natural.

The multi-value conversion method performed at the multi-valueconversion unit 23 is also characterized in that in the case where valueof remarked pixel is black (1) side of two gradations and is positionedat the boundary between black area and white area, value of remarkedpixel is set to the minimum value (0) of multi-gradation or the minimumneighboring value (1 or 2 here). For example, T[1][214] when A=1 andB=214, i.e., value of remarked pixel is black (1) side of two gradationsand surrounding eight pixels are (11010110) are set to 2 as shown inFIG. 27.

When the remarked pixel is 1 and the surrounding eight pixels are(11010110) as shown in FIG. 37, since the surrounding successive threepixels are 0 and the remaining pixels are 1, it is judged thatcorresponding pixels are pixels on the boundary to set that value to 2,etc. Thus, it is possible to set density at the boundary portion ofimage to value different from other portion. As a result, it is possibleto provide the effects/advantages of blurring prevention at the boundarybetween solid portions of different colors and/or blurring prevention ofedge of character.

While table example where value of multi-valued T[A][B] is set toquinary data (value) from 0 to 4 is shown in FIGS. 5 to 28, tableexample in the case where that value is set to sexenary data (value)from 0 to 5 can be also prepared as shown in FIG. 38 on the basis of thepreviously described multi-value conversion method. Here, when, e.g.,A=1 and B=1, i.e., when value of the remarked pixel A is black (1) sideof two gradations and the surrounding pixels are (00000001), value ofT[A][B] is set to (2) of multi-gradation. In addition, when A=1 andB=255, value of T[A][B] is set to the maximum value (5) ofmulti-gradation.

The practical example for converting binary data into sexenary data willbe described below by using FIGS. 39 to 44. This processing is aprocessing such that, e.g., binary data of C (cyan) is delivered fromthe expansion unit 22 to the multi-value conversion unit 23 in FIG. 3 toconvert binary data of C (cyan) into sexenary data with reference to thetable shown in FIG. 38 at the multi-value conversion unit 23.

When A is 1 and B is 0 (binary number: 00000000) as shown in FIG. 39,the multi-value conversion unit 23 takes out T[A][B] from the tableshown in FIG. 38 to allow remarked pixel A′ to be equal to 1.

When A is 1 and B is 255 (binary number: 11111111) as shown in FIG. 40,the multi-value conversion unit 23 takes out T[A][B] from the tableshown in FIG. 38 to allow remarked pixel A′ to be equal to 5.

When A is 1 and B is 1 (binary number: 00000001) as shown in FIG. 41,the multi-value conversion unit 23 takes out T[A][B] from the tableshown in FIG. 38 to allow remarked pixel A′ to be equal to 2.

When A is 1 and B is 90 (binary number: 01011010) as shown in FIG. 42,the multi-value conversion unit 23 takes out T[A][B] from the tableshown in FIG. 38 to allow remarked pixel A′ to be equal to 3.

When A is 1 and B is 248 (binary number: 11111000) as shown in FIG. 43,the multi-value conversion unit 23 takes out T[A][B] from the tableshown in FIG. 38 to allow remarked pixel A′ to be equal to 3.

When A is 1 and B is 244 (binary number: 11110100) as shown in FIG. 44,the multi-value conversion unit 23 takes out T[A][B] from the tableshown in FIG. 38 to allow remarked pixel A′ to be equal to 3.

The reason why the picture quality of binary data is poor is that dotsof high density are thinly printed particularly at the highlightportion. In view of the above, if printer 20 which permits, e.g., printof quinary or sexenary data is used to set conversion table as shown inFIGS. 5 to 28 or FIG. 38, e.g., in the case of isolated dot, conversioninto 1 is made. As a result, since dots of low density are printed,granular feeling is lowered so that picture quality can be improved.Moreover, since in the case where dots exist at all surroundingportions, conversion into 4 or 5 of high density can be made, and in thecase where dots thinly exist at the surrounding portion, conversion into2 or 3 can be made, print in conformity with gradation can be made.Further, in the case where value of remarked pixel is black (1) side oftwo gradations, and exists at the boundary between black area and whitearea, value of the remarked pixel is set to the minimum value (0) orvalue in the vicinity of the minimum value (1, 2 or 3) ofmulti-gradation, thereby also making it possible to lower level of theedge portion. This is effective particularly for ink jet printer, andpermits elimination of blurring of the edge portion of character, etc.,or reduction in color bleed taking place at the boundary portion betweensolid portions of different colors.

The processing performed in the print system 1 which has been explainedabove are collectively shown in FIG. 45. This includes practical exampleof print method of the present invention.

First, processing performed at the computer device 10 are shown at stepsS1 to S3. The computer device 10 converts, at step S1, RGB image data ofrespective 8 bit 256 values of image file 2 a into data of cyan (C)component, data of magenta (M) component and data of yellow (Y)component, e.g., respectively consisting of 8 bits which complementarycolors of three primary colors (red, green, blue) by using, e.g.,three-dimensional look-up table, etc. to further generate data of black(K) component of 8 bits from data of these components. In addition,signal processing such as color correction or γ-correction, etc. isimplemented to data of cyan (C) component, data of magenta (M) componentand data of yellow (Y) component.

Then, the computer device 10 converts, at step S2, data of the cyan (C)component, data of magenta (M) component, data of yellow (Y) component,data of black (K) component into binary data of respective 1 bits byusing the half-toning technology, e.g., error diffusion method orpattern Dither method, etc.

At step S3, CMYK respective binary data to which half-toning processinghas been implemented are compressed in order to further improve transferefficiency to add information necessary for performing the print asheader to generate print data D_(PR).

The step S4 is processing for data transfer.

Meanwhile, in the conventional processing, as shown in FIG. 46,conversion into data of CMYK respective quinary data is performed athalf-toning processing of step S12 after color conversion+γ-correctionprocessing of step S11 to compress the data thus obtained at step S13 toallow it to be print data D_(PR). Accordingly, it took much time in datatransfer processing of step S14.

On the contrary, in the data transfer of step S4, since image data isconverted into binary data at the step S2, data quantity can be reducedto much degree. Thus, data transfer time can be shortened.

At the printer 20 side, when print operation is performed under thestate of binary data, only printed result of low picture quality can beobtained. In view of the above, in the print system 1, at the printer20, binary data is converted into multi-valued, e.g., quinary orsexenary data in a manner previously described. The processing in FIG.45 is processing of step S6.

First, at step S5, the printer 20 receives print data D_(PR) which hasbeen caused to undergo data transfer (step S4) to take out informationnecessary for performing print operation from the print data D_(PR), andto expand compressed image data to change it back into CMYK respective 1bit binary data.

Then, at the step S6, the expanded CMYK respective 1 bit binary data areconverted into, e.g., quinary or sexenary data on the basis of thepreviously described multi-value conversion method.

The CMYK respective multi-valued data which are multi-valued are sortedat step S7 in drive order of the printer head 21 to generate head drivedata D_(HD).

In the conventional processing example shown in FIG. 46, since datatransfer at step S14 is performed by quinary data, CMYK respectivequinary data are obtained after expansion is performed at step S15. As aresult, multi-value conversion processing like the step S6 of FIG. 45becomes unnecessary. Thus, it is possible to shift to sort processing ofstep S16. The time required for step S6 which is data processing at theprinter side is extremely smaller than data transfer time. The printersystem 1 of this embodiment can shorten total printing time to moredegree.

Further, in the print system 1, since binary data is converted intomulti-valued data, it is possible to obtain printed matter of highpicture quality as compared to simple binary data. That picture qualityis not particularly so inferior as compared to printed matter of theprint system of the conventional example which performs processing shownin FIG. 46.

The effects or advantages of the print system 1 of this embodiment whichhas been explained are summarized below.

First, in accordance with the print system 1, since data sent from thecomputer device 10 to the printer 20 is binary data, there are manymerits that data quantity is reduced so that data transfer time becomesshort, and traffic on the network can be lessened, etc. In addition,since printed result is obtained as multi-valued data, printed result ofwhich picture quality is higher than that of binary image can beobtained.

At the printer 20, since gradation can be changed in dependency upon howdots around the remarked pixel are printed, it is possible to freelymake setting such that in the case where the number of dots is low atthe periphery, the density is lowered, or density is caused to be highat portions where peripheral dots are many, and/or the density of theedge portion of image is caused to be high or low.

At the printer 20, conversion processing from binary data tomulti-valued data is caused to be table in advance to thereby eliminatethe necessity of performing classification of various cases. Thus,processing can be performed at a high speed, and processing can beperformed without conducting conditional branch in performing parallelprocessing by DSP, etc.

At the computer device 10, since matrix Dither or error diffusion isused in binarizing original data, dots are thinly printed at highlightportion. In such case, since density of isolated dots can be set to lowvalue at the printer 20 side, it is possible to obtain printed matterhaving less granular feeling.

At the computer device 10, when matrix Dither or error diffusion is usedin binarizing original data, dots are thickly printed at high densityportion. In such a case, since density of successive dots is permittedto be high at the printer 20 side, density of the portion for which highdensity is required is caused to be high,

At the printer 20, it is possible to change level of edge portion ofimage. Particularly, in the case of ink jet printer, since ink quantityof the edge portion can be reduced by changing the level, it becomespossible to reduce blurring between colors and blurring onto paper.

At the printer 20, since level can be changed in accordance with thenumber of dots printed onto pixels around the remarked pixel, conversioninto low level can be made at low gradation where dots are thinlyprinted, and conversion into high level can be made at high gradationwhere dots are printed large number of times at the peripheral portions.

A practical example of the printer 20 will be explained below.

First, there is mentioned ink jet printer using line head in which alarge number of nozzles are arranged in a direction perpendicular topaper feed direction when recording paper of A4 size is printed in thelongitudinal direction as print head.

As shown in FIGS. 47 and 48, this ink jet printer 100 comprises a linehead 120 including heat element which will be described later as a driveelement which discharges droplets of ink, and having recording range ofsubstantially width size of paper P and having modulation function ofthe so-called PNM (Pulse Number Modulation) system which performsmodulation of diameter and density of dot by the number of droplets ofink. It is to be noted that the number of droplets printed with respectto 1 dot is set to eight (8) at the maximum per one color forexplanation in this case.

The ink jet printer 100 is caused to be of the configuration in whichline head 120, a paper feed unit 130, a paper delivery unit 140, a papertray 150 and an electric circuit unit 160, etc. are disposed within acasing 100.

The casing 100 is formed so as to take parallelepiped shape, wherein apaper eject hole 111 for paper P is provided at one end terminal sidesurface and a tray exit/entrance 112 for the paper tray 150 is providedat the other end side. The line head 120 comprises head portionscorresponding to four colors of CMYK (cyan, magenta, yellow, black),wherein an ink discharge portion which discharges ink droplets isdisposed at the end side upper portion of the paper eject hole 111 sidein such a manner directed downwardly.

Namely, as described later, this line head 120 is caused to be of theconfiguration in which four (in this case) ink discharge means in longform which are formed every respective colors as described later arearranged in feed direction of paper.

The paper feed unit 130 comprises a paper feed guide 131, paper feedrollers 132, 133, a paper feed motor 134, pulleys 135, 136, and belts137, 138, and is disposed at the end portion lower direction of thepaper eject hole 111 side. The paper feed guide 131 is formed so as totake flat plate shape, and is disposed at the lower direction of theline head 120 with a predetermined spacing. The respective paper feedrollers 132, 133 are comprised of a pair of rollers which are in contactwith each other, and are disposed at both sides of the paper feed guide131, i.e., the tray exit/entrance 112 side and the paper eject hole 111side. The paper feed motor 134 is disposed at the lower portion of thepaper feed guide 131, and is connected to the respective paper feedrollers 132, 133 through pulleys 135, 136 and belts 137, 138.

The paper delivery unit 140 comprises a paper delivery roller 141, apaper delivery motor 142 and gears 143, and is disposed at the trayexit/entrance 112 side with respect to the paper feed unit 130. Thepaper delivery roller 141 is formed so as to take substantiallysemi-cylindrical shape, and is disposed in the state close to the paperfeed roller 132 of the tray exit/entrance 112 side. The paper deliverymotor 142 is disposed above the paper delivery roller 141, and isconnected to the paper delivery roller 141 through the gears 143.

The paper tray 150 is formed so as to take box shape such that papers Pof, e.g., A4 size can be accommodated in the state where plural papersare stacked, wherein a paper support 152 held by a spring 151 isprovided at one end surface of the bottom surface, and is disposed in amanner extending from the lower portion of the paper delivery unit 140toward the tray exit/entrance 112. The electric circuit unit 160 is aportion for controlling drives of respective components, and is disposedabove the paper tray 150.

In such configuration, its operation example will be explained.

User draws the paper tray 150 from the tray exit/entrance 112 toaccommodate a predetermined number of papers P within the paper tray 150to push (thrust) it thereinto. Thus, the paper support 152 raises oneend portion of paper P by action of the spring 151 to push (thrust) ittoward the paper delivery roller 141. When print start signal is given,the paper delivery roller 141 is rotated by drive of the paper deliverymotor 142 to send out one paper P from the paper tray 150 to the paperfeed roller 132. Subsequently, respective paper feed rollers 132, 133are rotated by drive of the paper feed motor 134. As a result, the paperfeed roller 132 sends out the paper P which has been sent out to thepaper feed guide 131. Thus, the line head 120 becomes operative at apredetermined timing in accordance with data to be printed to dischargedroplets of ink from the ink discharge portion to get down them onto thepaper P to record characters or images consisting of dots, etc. Further,the paper feed roller 133 ejects, from the paper eject hole 111, thepaper which has been sent out.

Then, the internal configuration of the electric circuit unit 160 andthe block configuration of the peripheral portion thereof will beexplained by using FIG. 49.

The electric circuit unit 160 comprises a printer side data processingsection 161, a head controller 162, a head position and paper feedcontroller 163, and a system controller 164.

The printer side data processing section 161 executes the steps S5 to S7of FIG. 4 in order to realize the expansion unit 22, the multi-valueconversion unit 22 and the sorting unit 24 which are respectivefunctional blocks shown in the previously described FIG. 3. Namely, theprinter side data processing section 161 receives print data D_(PR)which has been caused to undergo data transfer to take out, from thisprint data D_(PR), information necessary for performing print operation,and to expand compressed image data to change it into CMYK respective 1bit binary data. Then, the expanded CMYK respective 1 bit binary dataare converted into, e.g., quinary or sexenary data on the basis of thepreviously described multi-value conversion method. The CMYK respectivemulti-valued data which have been multi-valued at step S7 are sorted indrive order of the line head 120 to generate head drive data D_(HD).

The head controller 162 controls ink droplet discharge operation of theline head 120. The head position and paper feed controller 163 controlsposition of the line head 120 and paper feed of the recording paper P.

The system controller 164 controls the printer side data processingsection 161, the head controller 162, and the head position and paperfeed controller 163.

Then, the detail of the line head 120 will be explained by using FIGS.50 to 54.

The line head 120 comprises a head chip module 201 a and a relay board201 b of which structures are shown in FIG. 54. First, the head chipmodule 201 a will be explained below. In this case, FIG. 50 is anexploded perspective view of the head chip module 201 a.

The head chip module 201 a comprises, as shown in FIGS. 50 and 51, anozzle formation member 202 formed so as to take substantially flatplate shape, which constitutes ink discharge surface.

At the nozzle formation member 202, there are formed a large number ofink discharge nozzles 203. In this example, several hundreds of inkdischarge nozzles 203 are respectively formed in line at positions wherehead chips which will be described later are disposed. The nozzleformation member 202 is formed so as to take sheet shape havingthickness of about 15 μm to 20 μm by using various electro-castingtechnologies with, e.g., nickel or material including nickel being asmaterial. Further, diameter of each ink discharge nozzle 203 is causedto be, e.g., about 20 μm. In addition, the nozzle formation member 202in which ink discharge nozzles 203 are formed is attached to a headframe 204.

The head frame 204 is adapted so that, e.g., three beam members 204 bare equidistantly bridged across short sides of an outer frame 204 acaused to have rectangular shape, and the outer frame 204 a and the beammembers 204 b are integrally formed. Namely, at the head frame 204, fourrectangular spaces 205 in which the outer frame 204 a is separated bythe beam members 204 b are constituted in parallel. Here, in the casewhere the head chip module 201 a is used for line head 120 whichsimultaneously prints one line with respect to paper, the length of thespace 205 is caused to be nearly equal to the length of one line printedat the same time. For example, in the case where the head chip module201 a is used for line head 120 which performs printing onto paper of A4size in longitudinal direction, the length of the space 205 is caused tobe the length corresponding to lateral width of paper of A4 size, i.e.,about 21 cm.

This head frame 204 may be formed by, e.g., silicon nitride, or may beformed by alumina, mullite, alimunum nitride, ceramic metal such assilicon carbide, etc. In addition, the head frame 204 may be formed byglass material such as quartz (SiO₂), etc., or metallic material such asinvarsteel, etc.

The head frame 204 has thickness of, e.g., about 5 mm, and has rigiditysufficient to support the nozzle formation member 202. The head frame204 and the nozzle formation member 202 are stuck to each other by,e.g., heat hardening type sheet-shaped adhesive agent.

At the nozzle formation member 202, there are disposed a large number ofhead chips 206. As shown in FIG. 52, the head chip 206 is adapted sothat plural heat resistors 208 are formed, by various thin filmformation technologies, on the principal surface of a base (substrate)207 formed by, e.g., silicon, etc. This heat resistor 208 is caused tobe of square shape in which one side is, e.g., about 18 μm.

On the base 207, a barrier layer 210 constituting the wall portion of anink pressure application chamber 209 is laminated on the surface wherethe heat resistors 208 have been formed. The barrier layer 210 is formedby, e.g., dry film resist having light hardening property, and is formedas the result of the fact that after the resist is laminated on theentire surface of the base 207, unnecessary portions are removed by thephotilithographic process. This barrier layer 210 is caused to havethickness of about 12 μm, and width of each ink pressure applicationchamber 204 is caused to be about 25 μm.

Here, when the case where the head chip module 201 a according to thisexample is used in the state mounted on line head having resolution 600dpi which prints paper of A4 size in longitudinal direction is assumed,the number of ink discharge nozzles 203 formed at the nozzle formationmember 202 every area of respective spaces 205 of the head frame 204approximately becomes equal to 5000. When the number of head chips 206disposed at the nozzle formation member 202 in this area is assumed tobe, e.g., 16, the number of ink discharge nozzles 203 corresponding toone chip 206 becomes equal to about 310. It is to be noted that thenumbers and sizes of respective components are indicated in exaggeratedor omitted manner for convenience of explanation in FIGS. 50 and 51.

At the head chip module 201 a, flow path plates 212 are attached torespective spaces 205 formed at the head frame 204 with respect to thenozzle formation member 202 where the head chip 202 is disposed.

As the flow path plate 212, there are four flow path plates incorrespondence with respective colors of inks. The flow path plate 212is formed by material having sufficient rigidity and ink resistancecharacteristic. The flow formation plate 212 is adapted so that achamber portion 213 fitted into the space 205 of the head frame 204 anda flange portion 214 formed in a manner projected toward one end portionof the chamber portion 213 are integrally formed.

The A–A′ cross section in FIG. 51 is shown in FIG. 53. The head chipmodule 201 a will be further explained by using FIGS. 51 and 53. Theflange portion 214 is formed in a manner to take plane shape larger thanplane shape of space 205 of the head frame 204. The chamber portion 213includes a space 215 shown in FIG. 51 opened to the end surface of theside opposite to the side where the flange portion 214 is formed. At thewall portion which limits both sides of the space 215, there is formed acut recessed portion 216 shown in FIGS. 51 and 53 for the purpose ofpositioning the head chip 206 in a manner communicating with the space215. In addition, at the flange portion 214, an ink supply tube 217 isprojected from the surface of the side opposite to the surface where thechamber portion 213 is extended. This ink supply tube 217 communicateswith the space 215.

The flow path plate 212 is connected to the head frame 204 in the statewhere the chamber portion 213 is fitted into the space 205 of the headframe 204, and the flange portion 214 is in contact with the beamportion 204 b of the head frame 204. The head chip 206 disposed at thenozzle formation member 202 is positioned within the cut recessedportion 216 formed at the chamber portion 213 of the flow path plate212, and is bonded to the chamber portion 213.

Thus, closed space surrounded by the chamber portion 213 of the flowpath plate 212 and the nozzle formation member 202 is formed. Thisclosed space communicates with the external through only the ink supplytube 217 and the ink discharge nozzle 203. Within the closed space, inkflow paths 218 are formed at the portions between rows of head chip 206in such a manner that they are alternately arranged (so called inzig-zag form) while adjacent ones overlap with each other. Therespective ink pressure chambers 209 shown in FIGS. 51 to 53 are placedin communicating state by the ink flow paths 218.

Ink supply tubes 217 provided at the flow path plates 212 arerespectively connected to ink tanks (not shown) where inks of colordifferent from each other are contained. Thus, inks are filled withinthe respective ink flow paths 218 and the ink pressure applicationchamber 209.

In the head chip module 201 a constituted as described above, inperforming printing with respect to paper, current pulses are deliveredfor a short time period, e.g., about 1 to 3 micro seconds with respectto the selected heat resistor 208 by command from the head controller162 (see FIG. 49). As a result, this heat resistor 208 is rapidlyheated. Thus, ink bubbles take place at the portion in contact with theheat resistor 208. By expansion/contraction of the ink bubbles, inkdroplets are discharged from the ink discharge nozzle 203, and areattached onto paper. In addition, ink is supplemented, through the inkflow path 218, within the ink pressure application chamber 209 fromwhich ink droplets have been discharged. In a manner as described above,printing with respect to paper is performed.

It is to be noted that while heat element is used as drive element fordischarging ink from the nozzle in the line head 120, piezo-electricelement represented by piezo element may be used to discharge ink fromthe nozzle. A practical example of line head 120′ using piezo-electricelement will be described below by using FIGS. 55 to 57.

FIG. 55 shows a perspective cross sectional structure of the line head120′, FIG. 56 shows a cross sectional structure when the line head 120′in FIG. 55 is viewed from direction indicated by arrow Z in FIG. 55, andFIG. 57 shows a cross sectional structure when the line head 120′ inFIG. 55 is viewed from the direction indicated by arrow W in FIG. 55. Asshown in these figures, the line head 120′ is caused to be of theconfiguration comprising a thin nozzle plate 121, a flow path plate 122laminated on the nozzle plate 121, and a vibration plate 123 laminatedon the flow path plate 122. These respective plates are stuck to eachother by, e.g., adhesive agent (not shown).

At the upper surface side of the flow path plate 122, there areselectively formed recessed portions. By these recessed portions and thevibration plate 123, plural ink chambers 124 and a common flow path 125communicating with these ink chambers are constituted. The communicatingportion where the common flow path 125 and the respective ink chambers124 communicate with each other is narrow. There is employed structuresuch that the flow path width becomes broader in accordance with shifttoward the direction of respective ink chambers 124 from thecommunicating portion. On vibration plates 123 immediately above therespective ink chambers 124, piezo-electric elements 126 comprised ofpiezo element, etc. are respectively fixed. On respective piezo-electricelements 126, electrodes (not shown) are respectively laminated andarranged. By applying a drive signal from the head controller 162 tothese electrodes, it is possible to bend respective piezo-electricelements, vibration plates in its turn, in the direction indicated byarrow E in FIG. 57 to increase (expand) or decrease (contract) capacityof the ink chamber 124.

The portion of the side opposite to the side communicating with thecommon flow path 125 at respective ink chambers 124 has the structure inwhich the flow path width gradually becomes narrow as shown in FIG. 55.At the flow path plate 122 of the terminating portion thereof, there isprovided a flow path hole 127. As shown in FIG. 56, this flow path hole127 communicates with a very small nozzle 128 formed at the nozzle plate121 of the lowermost layer so that ink droplets are discharged from thenozzle 128. At the line head 120, as shown in FIG. 55, there are formedplural nozzles 128 in line equidistantly along the direction Xperpendicular to the paper feed direction Y of recording paper P.

The common flow path 125 communicates with an ink cartridge 120 a (seeFIG. 49). Further, ink is delivered from the ink cartridge 120 a torespective ink chambers 124 via the common flow path 125. While thissuply of ink can be performed by making use of the capillary phenomenon,a predetermined pressure application mechanism may be provided at theink cartridge 120 a to apply pressure to perform such supply in place ofthe above.

Then, another practical example of the printer 20 will be explained.

Here, ink jet printer using print head reciprocating in the mainscanning direction is mentioned as the print head.

This jet printer 170 comprises, as shown in FIG. 58, print heads 171_(K), 171 _(C), 171 _(M), 171 _(Y) which respectively discharge inks ofblack (K), cyan (C), magenta (M), yellow (Y), a cartridge unit 173 towhich the print heads 171 _(K), 171 _(C), 171 _(M), 171 _(Y) areattached and serving to move these print heads 171 _(K), 171 _(C), 171_(M), 171 _(Y) in the main scanning direction, a flexible printed board174 which supplies a drive signal for driving the print heads 171 _(K),171 _(C), 171 _(M), 171 _(Y), a guide rail 175 for guiding the cartridgeunit 173, and a group of ink tanks 177 for supplying ink to respectiveprint heads through the ink supply pipe 176.

The group of ink tanks 177 supply inks of black (K), cyan (C), magenta(M), yellow (Y) to respective print heads through the ink supply pipe176. The print heads 171 _(K), 171 _(C), 171 _(M), 171 _(Y) are printheads of the ink jet type using, e.g., piezo element or heat element. Inorder to perform high speed print, plural nozzles which discharge inkare provided similarly to the line head 120 shown in FIGS. 55 to 57.These print heads 171 _(K), 171 _(C), 171 _(M), 171 _(Y) respectivelyselectively discharge, onto recording paper P, inks of black (K), cyan(C), magenta (M), yellow (Y) on the basis of drive signal deliveredthrough the flexible printed board 174 to perform print operation.

Three kinds of ink jet printers have been mentioned above as practicalexample and other practical example of the printer 20. In the ink jetprinter, blurring, etc. may take place at edge portion of charcter, etc.in dependency upon the characteristic of paper. However, in accordancewith the printer 20, since level of the edge portion can be lowered, itis possible to eliminate blurring. Namely, the present invention iseffective when applied to the ink jet printer.

It is to be noted that while the example where binary data is convertedinto quinary or sexenary data at the multi-value conversion unit 23 ofthe printer has been mentioned, it is possible to convert binary datainto multi-valued data such as trinary, quartary (4-ary), and septary(7-ary) or more data in conformity with ability of the printer 20.

Moreover, value of multi-value conversion may be selected in conformitywith the characteristic of recording paper. Further, there may beemployed print system capable of performing both processing from binarydata to multi-valued data shown in FIG. 45 and the conventionalprocessing shown in FIG. 46 and adapted to selectively perform eitherone of them by instruction of user.

While eight pixels positioned in upper and lower directions, in left andright directions and in oblique direction are caused to be object pixelsin the above-described embodiments with respect to the number n ofpixels around the remarked pixel, n may be integer of 3 or more, e.g.,4, 5 . . . , 12 . . . 16 . . . 24 . . . 32.

Finally, printed results obtained by the print system 1 to which thepresent invention is applied are shown in FIGS. 59A to 59C, FIGS. 60Aand 60B while making comparison to the conventional example.

FIG. 59A is printed matter by data transfer in the state of multi-valueddata which is obtained by the conventional processing example shown inFIG. 46. FIG. 59B is printed matter directly obtained by binary dataafter data transfer is performed at binary data. As a result, onlyprinted matter having strong granular feeling and low picture qualitycan be obtained. FIG. 59C is printed matter obtained by the print system1. Printed result having small granular feeling when compared to FIG.59B and which is not so inferior even if comparison with FIG. 59A ismade.

FIGS. 60A and 60B are results in which character of 6 points is printedonto ordinary paper by the ink jet printer. Even if corresponding datais multi-valued data or binary data, blurring is conspicuous as shown inFIG. 60A in the conventional method. However, in accordance with theprint system 1, blurring can be reduced as shown in FIG. 60B.

It is to be noted that while the invention has been described inaccordance with preferred embodiments thereof illustrated in theaccompanying drawings and described in the above description in detail,it should be understood by those ordinarily skilled in the art that theinvention is not limited to embodiments, but various modifications,alternative constructions or equivalents can be implemented withoutdeparting from the scope and spirit of the present invention as setforth and defined by appended claims.

INDUSTRIAL APPLICABILITY

In the printer and the print method according to the present invention,conversion into data of multi-gradation including three gradations ormore is performed on the basis of data of pixels around the remarkedpixel at the time of print operation with respect to data of twogradations per one pixel. Accordingly, it is possible to obtain printedmatter of high picture quality from print data which has beentransferred in the state changed into 1 bit for the purpose ofshortening data transfer time.

The print system according to the present invention convertsmulti-valued data into binary data to transfer it to printer to convertbinary data into multi-valued data by using table at the printer.Accordingly, it is possible to perform data transfer in the state wheredata quantities of respective pixels are caused to have 1 bit to obtainprinted matter of high picture quality from data of 1 bit of respectivepixels which have been caused to undergo data transfer.

1. A print method for printing color images comprising: converting aCyan, Magenta, Yellow, Black (CMYK)-based multi-gradation perpixel-color image to an image of two gradations per pixel-color, furthercompressing the two-gradation image via a compression algorithm,transmitting the compressed two-gradation image to a printer,decompressing the compressed two-gradation image via a decompressionalgorithm, converting the two-gradation per pixel-color image to amulti-gradation per pixel-color image, and printing the image based onthe multi-gradation per pixel-color image data.
 2. A print method forprinting color images comprising: converting a Red, Green, Blue(RGB)-based color space image to a Cyan, Magenta, Yellow, Black(CMYK)-based color space image, converting the CMYK-basedmulti-gradation per pixel-color image to an image of two gradations perpixel-color, further compressing the two-gradation image via acompression algorithm, transmitting the compressed two-gradation imageto a printer, decompressing the compressed two-gradation image via adecompression algorithm, converting the two-gradation per pixel-colorimage to a multi-gradation per pixel-color image, and printing the imagebased on the multi-gradation per pixel-color image data.
 3. A printmethod for printing color images as disclosed in any one of claims 1 and2, wherein said two-gradation conversion process includes a dithering orerror-diffusion process.